The present invention relates to an emergency locator device, and more particularly to an inflatable balloon usable as an aloft emergency locator and its combination with an inflation gas supply device such as in the form of a hand size kit, as well as to a specific gas supply flow control assembly.
U.S. Pat. No. 2,570,549 to Hansell; U.S. Pat. No. 2,923,913 to McPherson et al; U.S. Pat. No. 2,888,675 to Pratt et al; U.S. Pat. No. 3,952,975 to Laske; U.S. Pat. No. 4,029,273 to Christoffel, Jr.; and U.S. Pat. No. 4,586,456 to Forward; show typical specifically shaped and dimensioned inflation balloons, some of which have so called "tuned" radar reflective surfaces, and which are usable as tether line attached emergency locators when allowed to rise and float aloft in the air to indicate, either visually or by radar scanning, the location of someone in distress at a remote area such as on the high seas, in a forest or jungle, or the like.
These locators are usually provided in kit form for manual or automatic inflation of the balloon, using various actuators to charge the balloon with inflation gas from a tank supply.
A distinct problem with the shape of the balloon is that it must be able to remain aloft under quiescent as well as turbulent wind and weather conditions. Thus, on the one hand, while a more spherical shaped balloon remains aloft efficiently under quiescent conditions, its performance is adversely affected by more turbulent conditions. On the other hand, while a more aerodynamic kite like shaped balloon, especially a winged balloon with web connections between the main body and wings, remains aloft somewhat efficiently under more turbulent conditions, it often cannot remain aloft properly under windless conditions.
Generally, it is well recognized that there are at least seven conflicting sets of parameters involved in optimizing a radar reflective and visual signal or locator spherical or kite type balloon. These are: (1) aerodynamic factors, (2) weight, (3) radar reflectivity, (4) size and convenience, (5) regulatory factors, (6) safety, and (7) cost. Obviously, any design which optimizes one area will suffer in others. For example, while a ten foot size balloon will be easier to spot than a one foot size type, cost, convenience, regulatory and other considerations may suffer.
These irreconcilable factors have severely limited the effectiveness of available types of inflation balloon locators and their associated gas supply devices.
Said U.S. Pat. No. 2,888,675 to Pratt et al; and U.S. Pat. No. 2,646,019 to Chetlan; U.S. Pat. No. 3,002,490 to Murray; U.S. Pat. No. 3,210,990 to Cantrell; U.S. Pat. No. 3,721,983 to Sherer; and U.S. Pat. No. 3,735,723 to Lutz; employ various combinations of a perforatable seal on the discharge spout of an inflation gas tank and a piercing member movable into piercing engagement with the seal, as an actuator to release the gas for charging a balloon such as a locator balloon, in some cases with appropriate flow openings downstream of the tank, i.e. along the path from the spout to the balloon, to provide necessary flow communication.
U.S. Pat. No. 3,332,390 to Ashline employs a robust washer threaded into the tank discharge spout in exterior abutting relation to a perforatable seal disk sitting on a shoulder in the spout, the washer having a large central opening so as to act as a striker for the rim of a piercing member to limit the depth of penetration of the seal disk when the member is urged toward the seal disk, and also to act as a wide central flow passage for the escaping gas, a complicated cylindrical concentric array of an expansion sleeve between a pair of multiple apertured caps being provided downstream of the tank to induce a fog condition in the gas being fed to an inflation balloon.
U.S. Pat. No. 2,684,180 to Allen concerns a classic dry chemical type large size invertible fire extinguisher, having an upright outer concentric chamber filled with extinguisher powder and an upright central chamber containing an upright tank filled with pressurized fluid and provided with a top discharge spout. The spout is internally threaded and has a shoulder at its inner end on which the rim of an inner centrally apertured dished disk is located. An outer perforatable flat seal disk is disposed on the rim of the apertured dished disk, such that the central dished portion of the apertured disk is spaced slightly inwardly of the plane of the separate seal disk, and a ring nut is screwed into the threaded spout to compress the seal disk against the dished disk as a gasket on the shoulder to seal mechanically the tank spout. The central aperture of the dished disk is sized to provide a fluid limiting flow opening to discharge the pressurized fluid at a powder agitating and entraining rate over a fire extinguishing time span.
For this purpose, in the Allen extinguisher, the pointed end of a movable piercing member normally projects into the spout within the ring nut in close facing relation to the seal disk, under the retracting force of a spring keeping the pointed end away from the seal disk. Upon inverting the extinguisher and striking it against the ground, the rear end of the piercing member is driven upwardly against the force of the spring to cause the pointed end to perforate the seal disk of the inverted tank, discharging a surge of fluid to agitate and entrain the likewise inverted mass of powder in the outer chamber for delivery to a flexible hose atatched via an elbow to an adjacent part of the extinguisher.
Clearly, for proper operation of the Allen extinguisher, the fluid must be stored in the tank at very high pressure to insure sufficient jet speed flow of fluid through the central aperture of the dished disk upon perforating the seal disk to transport large amounts of powder through the hose at a high rate for rapid fire fighting purposes, and the piercing member, spring, seal disk, apertured disk, and related parts, must be precisely sized and positioned relative to each other to prevent the piercing member from also striking the central aperture margins of the dished disk and uncontrollably enlarging the central aperture when the extinguisher is inverted and struck against the ground.
It will be appreciated that an inherent danger with conventional inflation gas supply devices for emergency locator balloons is that upon opening the tank spout, the initial surge of pressurized gas could locally strike the uninflated balloon interior with a jet force sufficient to cause the balloon to be perforated and rendered useless.
In this regard, one known commercial form of an emergency locator kit utilizes a pair of small size pressurized gas tanks, each equipped with a perforatable seal in its discharge spout, plus a corresponding piercing member movable into piercing engagement with the seal and an actuator to effect piercing movement of the associated piercing member, for inflating a single locator balloon with the separate charges of pressurized gas at a safe rate from the two tanks. This separate incremental charging avoids the danger of perforating the balloon as would occur if the full quantity of the needed inflation gas were stored in a single tank. This is because the use of a single tank would necessarily involve a much higher order of magnitude storage pressure and generally a larger tank, and upon tank spout seal perforation by the piercing member such arrangement would potentially deliver an initial surge of pressurized gas capable of perforating the uninflated balloon.
As to the gas itself, of course air and carbon dioxide are unsuitable because they are not lighter than air and a locator balloon filled with such a gas will not remain aloft under still wind conditions. Also, use of large volume size balloons requires large and heavy gas supply tanks and/or high storage pressures, adding to the cost and weight of the unit, and more especially to the danger inherently associated with high pressure storage tank systems. Even with a lighter than air gas such as helium stored at a safe pressure in a small size tank for inflation of a small size balloon, the unit is still subject to the problem traceable to the shape of the balloon itself.
Thus, for purely aerodynamic reasons, round balloons are useles ssince they tend to blow down immediately in modest winds, where was aerodynamically efficient pure kites are useless since they will not fly in zero winds as are common at night or in a fog when the signal locator is often most needed. While a lifting body of streamline shape such as a kite shaped and/or teardrop shaped inflated balloon is able to fly in the desired wind velocity range, it suffers generally from poor radar reflectivity, irrespective of the balloon material used since this result is purely a function of shape.
Although an ideal shape aerodynamically would be that akin to a military stealth bomber, such constitutes the worst possible radar reflector shape, an advantage for military purposes but a disadvantage for an emergency locator. For this reason, various attempts have been made at radar enhancement by use of radar reflective surfaces in conjunction with an aerodynamically efficient winged lifting body shape. Adding tails having aerodynamic stabilizing effect unfortunately is limited by mass and drag considerations. Indeed, the locator tails must be of properly selected width and length, made of appropriate material, and be lightweight for accommodating such mass and drag limitations.